BAGHDAD, Iraq – Insurgents unleashed a wave of car bombings across the capital yesterday, killing about a dozen people, despite stepped-up American and Iraqi security measures for this month’s elections. North of Baghdad, insurgents killed a British security officer and kidnapped a Japanese engineer, officials said.

Gunmen fired on the Baghdad office of a major Kurdish party and two senior officials escaped assassination in separate attacks in the north.

The American military put the death toll from the day’s Baghdad bombings at 26, saying the number was based on initial reports at the scene. Iraqi officials gave a lower toll – 12 people killed in the bombings and one at the Kurdish office.

Sunni Muslim insurgents have threatened to disrupt the elections, and the five car bombings – four within a span of 90 minutes – underscored the grave threat facing Iraqis at this watershed in their history. American and Iraqi forces have stepped up raids and arrests in Baghdad, Mosul, and other trouble spots as the elections approach.

Nevertheless, the attacks had little effect on preparations for the January 30 balloting, in which Iraqis will choose a 275-member National Assembly and regional legislatures. At Baghdad airport, Iraqi authorities yesterday received the largest shipment of ballot boxes and other election equipment to date.

Election official Farid Ayar said 90,000 ballot boxes had already been flown to Iraq along with millions of ballots printed mostly in Canada and Australia.

Throughout the morning yesterday, the routine clatter of big city traffic was punctuated by the crisp sound of distant explosions. U.S. military helicopters rattled low overhead, roaming the bright blue sky for any sign of trouble.

Al Qaeda’s branch in Iraq claimed responsibility for the first of the day’s blasts, which occurred about 7 a.m. at the Australian Embassy in the capital. A truck packed with explosives blew up outside the concrete barriers in front of the embassy, killing two people and wounding several, including two Australian soldiers.

“A lion of monotheism and faith … carried out a martyrdom operation nearby the Australian Embassy,” the group Al Qaeda in Iraq said in an Internet state ment. The group is led by Jordanian militant Abu Musab al-Zarqawi, who has allied himself with Osama bin Laden’s terror network.

Lieutenant Colonel Steven Boylan, director of the U.S. military press center, said U.S. officials could not explain the discrepancy between the American and Iraqi figures “but we are holding to our numbers.”

A half-hour after the embassy blast, another car bomb exploded at a police station next to a hospital in eastern Baghdad. The U.S. military said 18 were killed there, but the Iraqi Interior Ministry put the death toll at six, including a policewoman.

A third car bombing struck at the main gate to an Iraqi military recruiting center located at a disused airport in central Baghdad. Police said the driver told guards he was delivering potatoes and detonated his explosives at the gate, killing three Iraqi soldiers and injuring one American.

The U.S. military also said a car bomb detonated southwest of Baghdad International Airport, killing two Iraqi security guards. The fifth car bomb exploded around noon near a Shiite mosque and a bank in north Baghdad, killing one person and injuring another, police said.

Also in the capital, insurgents in a car fired on an office of the Patriotic Union of Kurdistan, killing one of its members and wounding another, party officials said.